The Ratio 1660/1690 cm(-1) measured by infrared microspectroscopy is not specific of enzymatic collagen cross-links in bone tissue
2011
Farlay, Delphine | Duclos, Marie-Eve | Gineyts, Evelyne | Bertholon, Cindy | Viguet-Carrin, Stéphanie | Nallala, Jayakrupakar | Sockalingum, Ganesh D. | Bertrand, Dominique | Roger, Thierry | Hartmann, Daniel J. | Chapurlat, Roland | Boivin, Georges | Institut National de la Santé et de la Recherche Médicale (INSERM) | Université de Lyon | Université de Reims Champagne-Ardenne (URCA) | Institut National de la Recherche Agronomique (INRA) | Unite Medicament Dynam Intracellulaire Architectu, CNRS, UFR Pharm ; Université de Reims Champagne-Ardenne (URCA)-Centre National de la Recherche Scientifique (CNRS) | Ecole Nationale Vétérinaire de Lyon (ENVL) | Matériaux, ingénierie et science [Villeurbanne] (MATEIS) ; Université Claude Bernard Lyon 1 (UCBL) ; Université de Lyon-Université de Lyon-Institut National des Sciences Appliquées de Lyon (INSA Lyon) ; Université de Lyon-Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS) | D. Farlay is recipient of a grant from GRIO (Groupe de Recherche et d'Information sur les Osteoporoses). Website: www.grio.org. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
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Afficher plus [+] Moins [-]anglais. In postmenopausal osteoporosis, an impairment in enzymatic cross-links (ECL) occurs, leading in part to a decline in bone biomechanical properties. Biochemical methods by high performance liquid chromatography (HPLC) are currently used to measure ECL. Another method has been proposed, by Fourier Transform InfraRed Imaging (FTIRI), to measure a mature PYD/immature DHLNL cross-links ratio, using the 1660/1690 cm(-1) area ratio in the amide I band. However, in bone, the amide I band composition is complex (collagens, non-collagenous proteins, water vibrations) and the 1660/1690 cm(-1) by FTIRI has never been directly correlated with the PYD/DHLNL by HPLC. A study design using lathyritic rats, characterized by a decrease in the formation of ECL due to the inhibition of lysyl oxidase, was used in order to determine the evolution of 1660/1690 cm(-1) by FTIR Microspectroscopy in bone tissue and compare to the ECL quantified by HPLC. The actual amount of ECL was quantified by HPLC on cortical bone from control and lathyritic rats. The lathyritic group exhibited a decrease of 78% of pyridinoline content compared to the control group. The 1660/1690 cm(-1) area ratio was increased within center bone compared to inner bone, and this was also correlated with an increase in both mineral maturity and mineralization index. However, no difference in the 1660/1690 cm(-1) ratio was found between control and lathyritic rats. Those results were confirmed by principal component analysis performed on multispectral infrared images. In bovine bone, in which PYD was physically destructed by UV-photolysis, the PYD/DHLNL (measured by HPLC) was strongly decreased, whereas the 1660/1690 cm(-1) was unmodified. In conclusion, the 1660/1690 cm(-1) is not related to the PYD/DHLNL ratio, but increased with age of bone mineral, suggesting that a modification of this ratio could be mainly due to a modification of the collagen secondary structure related to the mineralization process.
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